Surprise variation found in human genes

2019-03-06 12:06:01

By Emma Young There are an average of 14 versions of each human gene, new research has found. This unexpected amount of genetic variation should force a rethink on the human genome, says the team at Genaissance Pharmaceuticals based in New Haven, US. The team analysed 313 genes from 82 Americans from four racial backgrounds. Estimates vary, but there is probably a total of about 30,000 human genes. “We’ve looked at the largest number of individuals and diverse populations that’s ever been done,” said Gerald Vovis, Genaissance chief technology officer. “The most surprising finding was the fact that we found an enormous variation within these genes which had not been known before.” The new study suggests that while humans have only 30,000 genes, there are between 400,000 and 500,000 gene versions. Vovis said these differences might partly explain why people respond so differently to the same medications. Francis Collins, director of the National Human Genome Research Institute in the US told Reuters: “We have been talking a lot about how similar all our genomes are, that we’re 99.9 per cent the same. That might tend to create an impression that it’s a very static situation. But that 0.1 per cent is still an awful lot of nucleotides.” The Genaissance team analysed SNPs – small stretches of DNA where there is known to be a high degree of variation between people. But, rather than looking at individual SNPs, they studied closely bunched sets which are inherited together, called haplotypes. The number of different haplotypes for each of the 313 genes varied from two to 53, but the average was 14. The team studied haplotypes from 21 whites, 20 blacks, 20 people of Asian descent, 18 Latinos and three Native Americans. They found no variation between gene versions that could define any one of the ethnic groups, Volvis said. But they did find that different versions of a gene are more common in a group of people from one geographical region, compared with people from another. The company says it hopes to catalogue the haplotypes of every human gene by analysing DNA from 90 people from Africa,